A new cardiid bivalve from the Pliocene Baklan Basin (Turkey) and the origin of modern Ponto‐Caspian taxa

Abstract: We present the first record of the cardiid genus Monodacna from the Pliocene of Anatolia, Turkey. Monodacna imrei sp. nov. was found in the Pliocene Killik Formation from the western margin of the Baklan Basin, in very marginal brackish to freshwater lacustrine deposits. The new record extends the stratigraphic range of the modern Ponto‐Caspian genus back into the Pliocene and adds to earlier evidence that modern Ponto‐Caspian taxa originated in the Pliocene of south‐western Turkey.     

Trends and uncertainties in Siberian indicators of 20th century warming

Estimates of past climate and future forest biomass dynamics are constrained by uncertainties in the relationships between growth and climatic variability and uncertainties in the instrumental data themselves. Of particular interest in this regard is the boreal-forest zone, where radial growth has historically been closely connected with temperature variability, but various lines of evidence have indicated a decoupling since about the 1960s. We here address this growth-vs.-temperature divergence by analyzing tree-ring width and density data from across Siberia, and comparing 20th century proxy trends with those derived from instrumental stations. We test the influence of approaches considered in the recent literature on the divergence phenomenon (DP), including effects of tree-ring standardization and calibration period, and explore instrumental uncertainties by employing both adjusted and nonadjusted temperature data to assess growth-climate agreement. Results indicate that common methodological and data usage decisions alter 20th century growth and temperature trends in a way that can easily explain the post-1960 DP. We show that (i) Siberian station temperature adjustments were up to 1.3 °C for decadal means before 1940, (ii) tree-ring detrending effects in the order of 0.6–0.8 °C, and (iii) calibration uncertainties up to about 0.4 °C over the past 110 years. Despite these large uncertainties, instrumental and tree growth estimates for the entire 20th century warming interval match each other, to a degree previously not recognized, when care is taken to preserve long-term trends in the tree-ring data. We further show that careful examination of early temperature data and calibration of proxy timeseries over the full period of overlap with instrumental data are both necessary to properly estimate 20th century long-term changes and to avoid erroneous detection of post-1960 divergence.     

Earlier onset of the spring phytoplankton bloom in lakes of the temperate zone in a warmer climate

The decoupling of trophic interactions is potentially one of the most severe consequences of climate warming. In lakes and oceans the timing of phytoplankton blooms affects competition within the plankton community as well as food–web interactions with zooplankton and fish. Using Upper Lake Constance as an example, we present a model‐based analysis that predicts that in a future warmer climate, the onset of the spring phytoplankton bloom will occur earlier in the year than it does at present. This is a result of the earlier occurrence of the transition from strong to weak vertical mixing in spring, and of the associated earlier onset of stratification. According to our simulations a shift in the timing of phytoplankton growth resulting from a consistently warmer climate will exceed that resulting from a single unusually warm year. The numerical simulations are complemented by a statistical analysis of long‐term data from Upper Lake Constance which demonstrates that oligotrophication has a negligible effect on the timing of phytoplankton growth in spring and that an early onset of the spring phytoplankton bloom is associated with high air temperatures and low wind speeds.     

Out of Asia and into India: on the molecular phylogeny and biogeography of the endemic freshwater gastropod Paracrostoma Cossmann, 1900 (Caenogastropoda: Pachychilidae)

Pachychilidae are distributed in the tropical regions of the southern continents implying a Gondwanan history. In the present study, we investigate the phylogenetic relationships of the freshwater pachychilid gastropod Paracrostoma endemic to Southern India using molecular genetic and morphological data, including the first examination of soft body material of the type species, Paracrostoma huegelii . In addition, two new species, Paracrostoma tigrina sp. nov. and Paracrostoma martini sp. nov. , are described. Our systematic revision shows that former taxonomic concepts of Paracrostoma were misleading. We demonstrate that the monophyletic Paracrostoma is restricted to Southern India and nested within a clade of South-east Asian taxa composed of Brotia and Adamietta . The mitochondrial phylogeny is corroborated by the presence of a subhaemocoelic brood pouch that represents a synapomorphy shared by members of only this group of taxa from the Asian mainland and India. Thus, in contrast to several other zoogeographical model cases, our study suggests that pachychilid freshwater gastropods colonized India out of South-east Asia, probably after the collision of both landmasses during the Eocene. By contrast, a simple vicariance scenario involving the Mesozoic raft of originally Gondwanan elements on the drifting Madagascar–India plate and later colonization of Asia from India fails to explain this distributional pattern. Therefore, Pachychilidae do not follow the predictions of the vicariant biotic ferry hypothesis, which has been suggested for a number of other organisms. We conclude that the origins of the Indian biota are more complex and diverse than assumed under the standard Mesozoic vicariance model.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 627–651.     

Comparative morphology among trunk limbs of Caenestheriella gifuensis and Leptestheria kawachiensis (Crustacea: Branchiopoda: Spinicaudata)

Morphological differences among groups of the 24 trunk limbs of Caenestheriella gifuensis (Ishikawa, 1895) and differences between males and females are described and illustrated. A setose attenuate lobe located proximally near enditic lobe 1 and a discoid lobe covered with small setae proximal to enditic lobe 1 are newly described. The five ventral enditic lobes, endopod, exopod, and dorsal exite of traditional spinicaudatan morphology are redescribed. Trunk limbs 1–4 of females bear a palp on enditic lobe 5 and trunk limbs 1–15 of males bear a similar palp. A second, articulating palp is associated with the base of the endopod of trunk limbs 1–2 of males. The proximal part of trunk limbs 19–24, bearing enditic lobe 1, articulates by an arthrodial membrane with the remainder of the limb, and the exite is distal to this arthrodial membrane. Development of trunk limbs, ascertained through an examination of early juvenile instars of Leptestheria kawachiensis Uéno, 1927, includes an asetose limb followed in time by a series of setose limbs that increase in morphological complexity with age. The number of lobes on the asetose limb varies from seven (corresponding to five enditic lobes, an endopod, and an exopod) on anterior limbs to five on trunk limb 24, which lacks the lobes corresponding to enditic lobe 4 and the endopod; these two structures are added later to setose limbs. The attenuate lobe, the discoid lobe, the exite of all trunk limbs, and the palps of the anterior trunk limbs are added to the setose limbs. Development of anterior limbs is accelerated relative to that of posterior limbs, and development of the more posterior limbs is truncated relative to that of limbs immediately anterior to them. Enditic lobe 4 and the endopod of limbs like trunk limb 24 develop from, or are patterned by, enditic lobe 5; the articulating palp of male trunk limbs 1–2 also may be added in this way. A comparison of these observations with development of the copepod maxilliped suggests that the spinicaudatan trunk limb is composed of a praecoxa with three lobes, a coxa and a basis each with one lobe, and an endopod of three segments in females and four in males. This is similar to the homology scheme previously proposed by Hansen in 1925. A critique is given of attempts to homologize parts of arthropod limbs based on developmental gene expression patterns. Stenopodal to phyllopodal transformations of maxillipeds in copepods provide a model at least partly applicable to spinicaudatans, and a ‘multibranched’ interpretation of spinicaudatan (and by extension branchiopodan) limb morphology is rejected. There is nothing intrinsic to the structure of the adult trunk limbs suggesting that they are similar to the adult limbs of the ancestral branchiopod or the ancestral crustacean, but early developmental steps of more posterior limbs are good matches for the morphology of an ancestral crustacean biramal limb predicted by a hypothesis of duplication of the proximo‐distal axis. © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society, 2003, 139 , 547–564. No claim to original US government works.     

Feeding deterrent effect of carvone, a compound from caraway seeds, on the slug Arion lusitanicus

The feeding deterrent effect of carvone on the slug Arion lusitanicus was investigated. Carvone, a natural compound from caraway seeds, was incorporated into mulch to reduce its inherent volatility. In a laboratory choice experiment, boxes were filled on one side with carvone‐treated mulch and on the other side with untreated mulch. At carvone concentrations ranging from 0.03–0.75 ml litre^?1 mulch, slugs ate significantly more lettuce on the untreated side. In a laboratory based no‐choice experiment, carvone concentrations of 0.25 and 0.75 ml litre^?1 mulch significantly reduced slug feeding in comparison with the untreated control. Moreover at the highest concentration of carvone (0.75 ml litre^?1 mulch) 50% mortality was recorded over a period of 5 days, indicating a clear molluscicidal effect. Due to its volatility carvone did not decrease plant defoliation by A. lusitanicus when applied directly onto lettuce. Subsequent field evaluation showed 0.75 ml litre^?1 mulch to partially reduce slug feeding damage. However, this effect was not sufficient to significantly increase lettuce yield. The incorporation of a higher carvone concentration into mulch is still to be tested to confirm whether carvone‐treated mulch can be recommended as an effective alternative approach to chemical slug control.     

Using geophysical information to define benthic habitats in a large river

1. Most attempts to describe the distribution of benthic macroinvertebrates in large rivers have used local (grab‐scale) assessments of environmental conditions, and have had limited ability to account for spatial variation in macroinvertebrate populations. 2. We tested the ability of a habitat classification system based on multibeam bathymetry, side‐scan sonar, and chirp sub‐bottom seismics to identify large‐scale habitat units (‘facies’) and account for macroinvertebrate distribution in the Hudson River, a large tidal river in eastern New York. 3. Partial linear regression analysis showed that sediment facies were generally more effective than local or positional variables in explaining various aspects of the macroinvertebrate community (community structure, density of all invertebrates, density of fish forage, density of a pest species –Dreissena polymorpha). 4. Large‐scale habitats may be effective at explaining macroinvertebrate distributions in large rivers because they are integrative and describe habitat at the spatial scales of dominant controlling processes.     

Atmospheric nitrogen deposition in world biodiversity hotspots: the need for a greater global perspective in assessing N deposition impacts

Increased atmospheric nitrogen (N) deposition is known to reduce plant diversity in natural and semi‐natural ecosystems, yet our understanding of these impacts comes almost entirely from studies in northern Europe and North America. Currently, we lack an understanding of the threat of N deposition to biodiversity at the global scale. In particular, rates of N deposition within the newly defined 34 world biodiversity hotspots, to which 50% of the world's floristic diversity is restricted, has not been quantified previously. Using output from global chemistry transport models, here we provide the first estimates of recent (mid‐1990s) and future (2050) rates and distributions of N deposition within biodiversity hotspots. Our analysis shows that the average deposition rate across these areas was 50% greater than the global terrestrial average in the mid‐1990s and could more than double by 2050, with 33 of 34 hotspots receiving greater N deposition in 2050 compared with 1990. By this time, 17 hotspots could have between 10% and 100% of their area receiving greater than 15 kg N ha^?1 yr^?1, a rate exceeding critical loads set for many sensitive European ecosystems. Average deposition in four hotspots is predicted to be greater than 20 kg N ha^?1 yr^?1. This elevated N deposition within areas of high plant diversity and endemism may exacerbate significantly the global threat of N deposition to world floristic diversity. Overall, we highlight the need for a greater global approach to assessing the impacts of N deposition.